Subcontractor gets a grip on productivity

Leaving the comfort of employment and starting a business is a decision loaded with emotion and taken with cautious trepidation. For the two ex-aerospace engineers that founded GD Precision, re-mortgaging their homes to finance the leap emphasises their confidence and passion. Some 17 years later and the decision has paid dividends for the West Sussex entrepreneurs.

Now operating from a 4400 sq ft facility in Arundel, the company has seven staff, a host of Mazak, XYZ and Dugard CNC machine tools, and a list of clients that span across the Formula One, aerospace, transport and medical industries. Like most subcontract machine shops, GD Precision is continually striving for cost reductions, efficiency, productivity and quality. Luckily, the company has many of these facets covered by cutting tool supplier, Industrial Tooling Corporation (ITC).
Recalling life before the cold call of ITC sales engineer Dave Cleeve some 10 years ago, company director Dale Buckthorpe says: “In the early days we were conscious of our spending and watched every penny. We would buy low-cost tools from a variety of suppliers, and when the tools were near burn-out, we would get buckets of tools re-ground. Of course, this was a false economy. When Dave Cleeve came in with tools that were considerably more expensive than the cheap tools we were using, we took some convincing.”
Taking up the story, fellow director and head of the milling department, Gary Short, says: “Dave from ITC reviewed our workload and offered us the 3081 series square-end, three-flute, solid-carbide end mill. At the time, we were using a 20 mm diameter ripper cutter from another supplier to machine an aluminium component at the full 20 mm width – at a depth of 0.5xD – applying a low feed rate. Taking-on-board Dave’s expertise, we applied the 3081 series at full flute depth with smaller cuts, at speeds and feeds that were remarkably high. We were sceptical, but we trusted Dave and immediately realised cycle time reductions of 50%.
“Not only did we achieve 50% cycle time reductions, but the surface finishes and tool life were anything from four to five times better than our previous tools,” he continues. “While we instantly realised the benefits of paying more for tools from a premium brand manufacturer like ITC, we also recognised the technical expertise was invaluable.”
This success noted the arrival of a full line of 3081 end mills from 6 to 20 mm diameter for everything from roughing to finishing applications.
“The 3081 series blew our previous tools away,” says Short. “It’s a general purpose end mill with a high helix that we now use for just about every aluminium machining task. We have recently been machining dental mould tools and the 3081 series is achieving 70+ hours of trochoidal machining on high-grade HE15 aluminium.”
ITC’s 3081 series soon became the tool of choice for all aluminium machining tasks at GD Precision, giving the directors confidence to trial further ITC tools. This followed in the guise of the ITC Widia VariMill range of TiAlN coated four-flute end mills for machining stainless steel and exotic materials. Instantly outperforming previous tools, the VariMill proved every bit as successful on challenging materials as the 3081 showed on aluminium.

“It took us a while to adjust to the VariMill’s high speeds and feeds, but we are now hitting jobs faster with smaller cuts while pulling 30-40% less horsepower,” says Short. “We opted for more trochoidal milling and ITC was integral in the evolution of our machining strategies. With the VariMill generating 30-40% productivity improvements, and tool life gains of beyond 50%, we have phased out the majority of tooling from alternate suppliers.”
For dedicated high-speed roughing of challenging materials, GD Precision is now utilising the ITC 6051 series of six-flute centre-cutting end mills. As Short recalls: “The long length 6051 has a 60 mm flute length that permits higher material removal rates with excellent reach characteristics. There is very little depth in the flutes of the 6051 series and this increases strength and eliminates vibration, enabling us to run at 3 to 4 m/min. On materials like stainless, we are machining at feed of 0.2mm per tooth using the full 60 mm flute length.”
The success of the 3081 series, the VariMill and the 6051 series has seen GD Precision continually implement new machining strategies and tooling lines from ITC. Recent additions include the 4071 series for deburring and chamfering, 4011 series radius tools and 2001 series necked back tools for 3D and profile machining.
A newly added Dugard Eagle 1000+ machining centre with a Big-Plus logo on the spindle housing, is something which did not go unnoticed by Cleeve, who recommended that GD Precision should purchase a Big Kaiser face and taper contact Hi-Power milling chuck to complement the spindle interface.
“When Dave recommended we try the BBT40 Hi-Power milling chuck, we trusted his judgement based on previous results – we were not disappointed,” says Short. “The Dugard machines are very robust and stable, but we were struggling to reach ITC’s recommended speeds and feeds. As soon as the Big Kaiser Hi-Power milling chuck arrived, we knew the weak link was our old milling chucks. With the Big-Plus we can reach the recommended speeds and feeds with no chatter and vastly improved surface finishes. Without the Big-Plus chuck, we have to reduce our cutting parameters by at least 25%.
“The Big-Plus Hi-Power has improved our tool life by at least 20%, increased our machining performance and cutting parameters by over 25%, and the run-out is well below 5 µm. In fact, we don’t have equipment accurate enough to measure how little run-out there is.
“The Big-Plus milling chuck allows us to run the VariMill 12 and 16 mm diameter tools with a trochoidal strategy on stainless steel at machining feeds of 100 m/min and a spindle speed of 2000 rpm. In fact, since applying the chuck, we have realised there is little point in buying high-end tools without this rigid system. By using the chuck with trochiodal strategies, we have reduced our cycle time on dental mould tools from 12 minutes to 6 minutes 45 seconds, a 45% cycle time improvement.”

Despite all the strategic, purchasing and manufacturing enhancements instigated by ITC, there is one habit the company has not dropped, as Short concludes: “We still collect boxes of used solid carbide end mills. The difference now is that ITC is a UK manufacturer, and we are returning the cutting tools to the OEM for regrinding. The benefit is that ITC has the geometries of all its tools and the regrinds are conducted on the same machines that produced them in the first place. This means that we get our re-ground tools returned in an ‘as-new’ condition at a fraction of the cost of new tools.”
For further information www.itc-ltd.co.uk

Half-year results show demand

Mills CNC’s half-year results show no let-up in demand for Doosan machine tools among UK and Irish component manufacturers.

The headline news is that for the period January to 18 June, orders for 240 new Doosan machines were taken by Mills. This strong showing comes off the back of a successful MACH 2018, where Mills sold 20 machines during the week-long event. Over 3000 people visited Mills’ stand at the show.
Over the past 18 months there has also been a noticeable upturn in demand for Mills’ turnkey and process improvement solutions. Says managing director Kevin Gilbert: “Delivering often complex, right-first-time turnkey solutions is a hallmark of Mills. More and more customers operating in the aerospace, defence and energy sectors, for example, are approaching us to help design and implement solutions that will help improve their productivity, operational efficiency and machining performance.”
For further information www.millscnc.co.uk

Power chuck offers pendulum compensation

Schunk has expanded its product range with a sealed six-jaw pendulum compensation chuck for clamping deformation-sensitive workpieces.

The special seals located on the serrated jaw interface and pistons of the Schunk Rota NCR-A stop grease from being flushed out and prevent the clamping force from being gradually lost.
According to the company, precise chuck function is assured, even at low clamping forces. In addition, the seal prevents chips or dirt from ingress into the chuck body. This increases process reliability and lengthens maintenance intervals, translating into less frequent lubrication and cleaning of the lathe chuck, says Schunk.
The Rota NCR-A consists of a central chuck piston carrying three inner pendulums aligned at 120°. Each pendulum is connected to two base jaws. This configuration ensures workpiece centering between six contact points, which can be adjusted in pairs. As the clamping forces are directed towards the chuck centre, optimal centering is achieved without distortion of the workpiece.
The chuck adjusts to the workpiece with its oscillating jaws. In the case of ring-shaped workpieces, deformation is reduced by a factor of 10 compared with clamping using three-jaw chucks. Users can also clamp the pendulum of the Rota NCR-A in the centre position during the final processing stage or when clamping pre-turned surfaces so that all six jaws move concentrically. The clamping force between the first and second clamping can be adjusted by means of a pressure reduction at the hydraulic cylinder.
For further information www.gb.schunk.com

Vice holds cylindrical or prismatic parts

The PC80Z self-centring vice from Roemheld is available in a new, two-in-one version that accepts the manufacturer’s optional round inserts, enabling cylindrical components or billets from 44 to 95 mm in diameter to be clamped securely. There is now no need for a machinist to buy a bespoke workholding solution or machine sets of soft jaws to hold parts of different diameters.

The vice can be converted back within a couple of minutes to its conventional role of holding prismatic components; it simply requires the Allen bolts holding four round inserts to be unscrewed and the pair of straight, 80 mm wide jaws to be reinstated. Parts from 17 to 139 mm long can then be secured for metal cutting using the 62 mm clamping stroke.
Of 60 mm overall height, the low-profile unit ensures that not much Z-axis travel is lost on a vertical machining centre. Additionally, despite its all-steel construction, the light weight of only 6 kg avoids taking up undue allowance from a machine’s maximum pallet load, enabling heavier parts to be produced.
Well suited to use on five-axis machining centres and in automated production cells employing pallet magazines, the vice is fitted as standard with the Lang interface for added versatility. Clamping force is 20 kN at 60 Nm closing torque. The device is said to be easy to disassemble and clean, minimising loss of productivity during routine maintenance.
For further information www.roemheld.co.uk

New centre jaw for five-axis vice

The Hoffmann Group has introduced a new module for its Garant Xpent five-axis vice.

This centre jaw, which can be optionally fitted to the base rail, has made it possible to clamp two workpieces with just one vice, and process them in a single operation. Such a configuration means clamping strategies that are more efficient can be implemented, leading to a measurable increase in productivity, says the company.
Garant Xpent vices are based on a modular design concept. Clamping modules, base rails and spindles can be individually combined and the convex clamping modules can be turned through 180°. Hoffman’s newly developed centre jaw offers another bonus, in terms of flexibility, and is immediately available as an accessory for sizes 0 to 1S (and will soon be available in sizes 1 and 2). The existing range of attachment rails, each with two clamping stages, is fully compatible with the new centre jaw.
Each vice has a clamping force of up to 40 kN at a torque of 90 Nm, and is available in three different heights and two widths. Base rails are available in lengths of 360 to 1050 mm. The new 1S size was specially developed for three- and five-axis machines with small
spindle gearboxes.
For further information www.hoffman-group.com